Pressure-boosting axial-flow heat-dissipating fan

ABSTRACT

A pressure-boosting axial-flow heat-dissipating fan includes a housing and an impeller. The housing includes an annular wall including an air inlet in a first end thereof and an air outlet in a second end thereof. A base and a pressure-boosting device are mounted in the air outlet. The impeller is rotatably mounted to the base. The impeller includes a hub and a plurality of blades on an outer periphery of the hub. Two of the blades adjacent to each other partially overlap with each other along an axis parallel to a rotating axis of the impeller. The number of the blades on the impeller is increased such that the overall air-driving area of the blades is increased, improving the overall heat-dissipating efficiency.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to an axial-flow heat-dissipating fan. In particular, the present invention relates to a pressure-boosting axial-flow heat-dissipating fan that provides increased air output and an air pressure-boosting effect.

2. Description of Related Art

U.S. Pat. No. 6,244,818 discloses a fan guard structure for additional supercharging function. The fan guard comprises a main frame, a motor holder, and a set of guard blades radially arranged inside the main frame and fixed onto an inner surface of the main frame by each one end thereof. A motor is mounted in the motor holder for driving a shaft ring with rotor blades. The set of guard blades can be arranged either upstream or downstream of the rotor blades. Each guard blade is preferred to have a shape similar to that of the rotor blades. The tangential velocity of the airflow is transformed into a static pressure when the motor turns. Accordingly, the blast pressure further rises through the fan guard, and the fan is thus supercharged.

However, due to limitation to the molding process, each rotor blade on the shaft ring is not overlapped with an adjacent rotor blade along an axis parallel to a rotating axis of the shaft ring such that the number of the rotor blades on the shaft ring is limited. The total air-driving area of the rotor blades is thus limited, leading to limitation to the surcharging (or pressure-boosting) effect. Further, the overall air output is still limited by the structure of the shaft ring although the guard blades provide a certain surcharging effect. In recent years, the shaft rings (or impellers) are manufactured by assemblage to increase the number of rotor blades. However, the shaft rings manufactured by assemblage have never been used with a fan guard providing an air pressure-boosting effect, nor has innovation in structure been made for improving air intake efficiency or improving air intake smoothness.

OBJECTS OF THE INVENTION

An object of the present invention is to provide an axial-flow heat-dissipating fan with increased air input and increased air output pressure, thereby improving the overall heat-dissipating efficiency.

Another object of the present invention is to provide an axial-flow heat-dissipating fan with increased air intake range.

SUMMARY OF THE INVENTION

In accordance with an aspect of the present invention, a pressure-boosting axial-flow heat-dissipating fan comprises a housing and an impeller. The housing includes an annular wall including an air inlet in a first end thereof and an air outlet in a second end thereof. A base and a pressure-boosting device are mounted in the air outlet. The impeller is rotatably mounted to the base. The impeller includes a hub and a plurality of blades on an outer periphery of the hub. Two of the blades adjacent to each other partially overlap with each other along an axis parallel to a rotating axis of the impeller. The number of the blades on the impeller is increased such that the overall air-driving area of the blades is increased, improving the overall heat-dissipating efficiency.

The hub is substantially inverted U-shaped and includes an arcuate portion adjacent to the air inlet side. Preferably, the air inlet of the housing is circular to allow smooth air intake.

In an embodiment of the invention, each blade includes an air-inlet-side tip substantially flush with an end face of the housing that is adjacent to the air inlet of the housing. The hub extends out of the air inlet of the housing.

In another embodiment of the invention, hub and the blades extend out of the air inlet of the housing, allowing the blades suck axial airflow and ambient radial airflow into the housing. Each blade includes an air-inlet-side tip at a level higher than the hub.

In an embodiment of the invention, the pressure-boosting device includes a plurality of radially extending plates each having a first end fixed to the base and a second end fixed to the annular wall. Preferably, each plate has a slant opposite to that of the blades with respect to the rotating axis of the impeller.

In another embodiment of the invention, the pressure-boosting device includes a plurality of parallel plates each of which is substantially triangular in section.

Other objects, advantages and novel features of this invention will become more apparent from the following detailed description when taken in conjunction with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is an exploded perspective view of a first embodiment of a pressure-boosting axial-flow heat-dissipating fan in accordance with the present invention;

FIG. 2 is a top view of the pressure-boosting axial-flow heat-dissipating fan in FIG. 1;

FIG. 3 is a sectional view of the pressure-boosting axial-flow heat-dissipating fan in FIG. 1;

FIG. 4 is an exploded perspective view of a second embodiment of the pressure-boosting axial-flow heat-dissipating fan in accordance with the present invention;

FIG. 5 is a sectional view of the pressure-boosting axial-flow heat-dissipating fan in FIG. 4;

FIG. 6 is an exploded perspective view of a third embodiment of the pressure-boosting axial-flow heat-dissipating fan in accordance with the present invention; and

FIG. 7 is a sectional view of the pressure-boosting axial-flow heat-dissipating fan in FIG. 6.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Referring to FIG. 1, a first embodiment of a pressure-boosting axial-flow heat-dissipating fan in accordance with the present invention comprises an impeller 1 and a housing 2. The impeller 1 improves the air-driving efficiency and the housing 2 increases the outputted air pressure, thereby improving the overall heat-dissipating efficiency.

Still referring to FIG. 1 and further to FIGS. 2 and 3, the impeller 1 comprises a hub 11, a plurality of blades 12 on an outer periphery of the hub 11, and a shaft 13. The hub 11 is substantially inverted U-shaped in section such that the hub 11 has an arcuate portion adjacent to the air inlet side. The blades 12 are inclined and symmetrically arranged on the outer periphery of the hub 11. Further, two blades 12 adjacent to each other partially overlap with each other along an axis X parallel to a rotating axis of the impeller 11. By this arrangement, the number of the blades 12 on the impeller 1 can be increased and the total air-driving area of the blades 12 is increased. In other words, the impeller 1 may drive more axial airflow. Further, the shaft 13 is fixed on a center of an inner side of the hub 11 for rotatably mounting the impeller 1 in the housing 2.

The housing 2 comprises an annular wall 20, a base 23 to which the shaft 13 is rotatably mounted, and a pressure-boosting device 24. The annular wall 20 includes an air inlet 21 in an end thereof and an air outlet 22 in the other end thereof. Preferably, the air inlet 21 is circular to provide smooth air intake. The base 23 and the pressure-boosting device 24 are mounted in the air outlet 22 of the housing 2. In this embodiment, the pressure-boosting device includes a plurality of radially extending plates 24 each having a first end fixed to the base 23 and a second end fixed to an inner periphery of the annular wall 20. Each plate 24 has a slant opposite to that of the blades 12 with respect to the rotating axis of the impeller. The pressure-boosting device 24 increases the outputted air pressure of the impeller 1.

As illustrated in FIG. 3, the impeller 1 is substantially received in the annular wall 20 of the housing 2, with an air-inlet-side tip 121 on each blade 12 being substantially flush with an end face of the housing 2 adjacent to the air inlet 21 and with the hub 11 of the impeller 1 slightly protruding out of the air inlet 21 of the housing 2. When the impeller 1 turns, more axial airflow is sucked into the air inlet 21 by the blades 12, as the total air-driving area of the blades 12 is greater than that of conventional designs. The arcuate portion of the hub 11 and the circular air inlet 21 smoothly guide axial airflow into the housing 2, and the pressure-boosting device 24 in the air outlet 22 increases the pressure of the axial airflow, providing an air pressure-boosting effect.

FIGS. 4 and 5 illustrate a second embodiment of the invention, wherein the blades 12 of the impeller 1 extend out of the air inlet 21 of the housing 2 for driving ambient air surrounding the housing 2 into the air inlet 21. The air intake range is increased. It is noted that the air-inlet-side tip 121 on each blade 12 is at a level higher than the hub 11. Further, the hub 11 and the blades 12 are outside the air inlet 21 of the housing 2. Thus, the blades 12 may drive axial airflow as well as ambient radial airflow into the housing 2.

FIGS. 6 and 7 illustrate a third embodiment of the invention modified from the first embodiment, wherein the pressure-boosting device includes a plurality of parallel plates 24′ in the air outlet 22 of the housing 2, forming a grill-like structure. Each plate 24′ is substantially triangular in section. The plates 24′ compress the output airflow to increase the air pressure. Further, the plates 24′ allow output of parallel airflows and/or guide the outputted airflow to dissipate heat in a specific direction.

While the principles of this invention have been disclosed in connection with specific embodiments, it should be understood by those skilled in the art that these descriptions are not intended to limit the scope of the invention, and that any modification and variation without departing the spirit of the invention is intended to be covered by the scope of this invention defined only by the appended claims. 

1. A pressure-boosting axial-flow heat-dissipating fan comprising: a housing including an annular wall, the annular wall including an air inlet in a first end thereof and an air outlet in a second end thereof, a base and a pressure-boosting device being mounted in the air outlet; and an impeller rotatably mounted to the base, the impeller including a hub and a plurality of blades on an outer periphery of the hub, two of the blades adjacent to each other partially overlapping with each other along an axis parallel to a rotating axis of the impeller.
 2. The pressure-boosting axial-flow heat-dissipating fan as claimed in claim 1 wherein the hub is substantially inverted U-shaped and includes an arcuate portion adjacent to the air inlet side.
 3. The pressure-boosting axial-flow heat-dissipating fan as claimed in claim 1 wherein each said blade includes an air-inlet-side tip substantially flush with an end face of the housing that is adjacent to the air inlet of the housing.
 4. The pressure-boosting axial-flow heat-dissipating fan as claimed in claim 1 wherein the hub extends out of the air inlet of the housing.
 5. The pressure-boosting axial-flow heat-dissipating fan as claimed in claim 1 wherein the blades suck axial airflow and ambient radial airflow into the housing.
 6. The pressure-boosting axial-flow heat-dissipating fan as claimed in claim 5 wherein the hub and the blades extend out of the air inlet of the housing.
 7. The pressure-boosting axial-flow heat-dissipating fan as claimed in claim 1 wherein each said blade includes an air-inlet-side tip at a level higher than the hub.
 8. The pressure-boosting axial-flow heat-dissipating fan as claimed in claim 1 wherein the air inlet of the housing is circular.
 9. The pressure-boosting axial-flow heat-dissipating fan as claimed in claim 1 wherein the pressure-boosting device includes a plurality of radially extending plates each having a first end fixed to the base and a second end fixed to the annular wall.
 10. The pressure-boosting axial-flow heat-dissipating fan as claimed in claim 1 wherein each said plate has a slant opposite to that of the blades with respect to the rotating axis of the impeller.
 11. The pressure-boosting axial-flow heat-dissipating fan as claimed in claim 1 wherein the pressure-boosting device includes a plurality of parallel plates.
 12. The pressure-boosting axial-flow heat-dissipating fan as claimed in claim 11 wherein each said plate is substantially triangular in section. 